RFR: 8220566: AArch64: Set default vm features for Ampere eMAG CPUs

[Andrew Dinn]

Hi Patrick,

On 14/03/2019 04:05, Patrick Zhang OS wrote:
> I added below comments in JIRA, also copied here. Thanks for your
> review.
> 
> https://bugs.openjdk.java.net/browse/JDK-8220566?focusedCommentId=14251292&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14251292
>  These three flags had been verified on Ampere eMAG platform with a
> couple of benchmarks and apps AvoidUnalignedAccesses=TRUE,
> UseSIMDForMemoryOps=TRUE can bring positive impact consistently,
> since access to odd alignment memory is not what we expect, and simd
> instructions replacement for mem/array copying practically helps
> performance. While for UseSIMDForArrayEquals=TRUE (default), I am not
> quite sure yet what took more execution time, either ld1 or umov, or
> the sequence generated inside generate_large_array_equals_loop_simd.
> Therefore I make it FALSE within a stricter condition for CPU
> revisions I have so far.

Thank you for making your decisions clear. I am happy to accept your
choice of defaults so this patch can be pushed. Do you need me to do
that for you?

regards,


Andrew Dinn
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